Of those patients who die in a medical intensive care unit (MICU), approximately 33% succumb to nosocomial pneumonia. Patients who are endotracheally intubated or tracheostomied for greater than 72 hours are especially prone to developing nosocomial pneumonia. The situation is further exacerbated when these patients are placed on artificial ventilation.
The most prominent factors that contribute to the pathogenesis of nosocomial pneumonia include: (1) mechanical impediment to mucocilliary clearance of lower respiratory tract secretions by cuffed endotracheal and trachostomy tubes at the level of the trachea; (2) colonization of the tracheabronchi with organisms from hands of health care workers; and (3) microaspiration via small leaks around cuffed endotracheal or tracheostomy tubes from the oropharynx into the respiratory tract.
Presently, repeated manual suction through the endotracheal/tracheostomy tubes facilitates clearing and aids in the prevention of stagnation of lower respiratory tract secretions. This is unfortunately effective only to a limited extent, as this process involves a high risk of introduction of organisms from health care workers in the upper respiratory tract, despite stringent sterilization efforts. An additional problem is the waste of valuable manpower as suction must be frequent to be effective.